High voltage battery packs comprised of prismatic cells, such as lithium ion batteries, may be provided in arrays that require cooling for efficient operation. Battery packs may be arranged in several ways including a parallel configuration in which all of the prismatic cells are aligned to be parallel to each other. Parallel fluid cooled arrangements have a common inlet plenum that provides fluid to each cell and into a common outlet plenum without passing other cells. In a parallel arrangement, all of the cells are evenly cooled to minimize cell-to-cell temperature differences. Parallel arrangements are difficult to package because they result in increasingly elongated configurations as the required voltage increases. In addition, venting requirements may make a parallel design unfeasible.
In a series arrangement, fluid flows from an inlet plenum past several battery cells or banks of battery cells before flowing into an outlet plenum. Series arrangements can be more easily packaged because the battery cells can be placed in several rows. However, fluid flowing through one cell passes through other cells in a series arrangement of battery cells. This approach leads to uneven cooling and large pressure drops across sequential rows.
Semi-parallel designs include batteries that arrange some battery cells in parallel and some in series in multi-row configurations. The minimum number of rows is two, but even this minimal number of rows may be adversely affected by excessive row-to-row pressure drop and cell-to-cell temperature differences from one row to another.
This disclosure addresses the above problems and limitations relating to battery cell arrangements and other problems as summarized below.